Abstract

Mice were selected in this study as a model to induce E.coli mastitis and sttudying the role of purified LPS in performed the protection against induce E.coli infection of mammary glands in mice. After LD50 of purified antigen were determined (250 µg/ml of purified LPS). The experimental study was included 56 mouse which divided into two groups and the LPS group was included 26 mouse, while the control group was included 30 mouse. The mouse in LPS group was immunized by: 2.5 µg of LPS /gm of mice and by sterile PBS (pH=7.2) in control group. In all groups, the route of inoculation was subcutaneous, and these doses repeated at 15 days, 27 days after first inoculation as boostered doses. At 34 days post the first inoculation the humoral and cellular immune response were assesement by many particular tests to determine the activity of their antigen in provided protection against challenge dose by virulent E.coli O111:B4 which gave intramammary, and histopathogical study was carried out in challenged mouse. The study was reported that LPS was possessed high and significant efficacy and potent ability to rise the humoral and cellular immune response and reduced significantly the severity of mammary gland infection in mouse with lowest histopathological change in mammary tissue when compared with control group as a good role of LPS in reduced severity of mammary gland infection when compared with control group.